Question

If x2 + xy + x=12 and y2 + xy + y = 18, then the value of x+yis
(A) 5 or -6
(B) 3 or 4
(C) 5 or 3
(D)​

Answer 1

Answer:

2x + xy + x = 12

3x +xy =12

xy = 12 -3x ------(1)

2y + xy + y = 18

3y + xy = 18

xy = 18 -3y --------(2)

From equation (1) & (2)

12 -3x = 18 -3y

3y - 3x = 6

y - x = 2

Answer 2

Answer:

A

Step-by-step explanation:

given equations

x2+xy+x=12

y2+xy+y=18

( add them)

x2+y2+2xy+x+y-30=0

(x+y)*2+(x+y)-30=0

let x+y=t

t2+t-30=0

(t+6)(t-5)=0

t+6=0,t-5=0

t=-6,t=5

therefore x+y= 5 or -6

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